1-1(> lAl.llCHtNlA .\iAI)|;MV (IK SCIUNCl-S. 



yubfaiiiily Jhsinina . 



Gciiiib Dosinia Scojivli. 



Slifll orbicular, compressed, concentrically striated, p.ilc, ligainciil .sunk; luiuilc deep; hinge 

 like Cyllierea: margin even; pallia! sinus deep, anj^iilar, ascending. 



Dosinia discus Reeve id a cliarucleristic species. 



[S. D] Dosinia ponderosa Gray. 



Artemis pondcrosa Gray, Analyst, Vol. VIII, 1838, p. 309. 



Dosinia ponderosa Gray, H. iv: A. Adams, Gen. Rec. Moll., Vol. II, jj. 432; ^=Cyllicrca gigantca 



Sby. (,Jide Gadb, Pal. Cal. Vol. II, p. 97, 1869). Cooper, 7th Ann. Rept. Cal. St. 



Min., 1888, p. 239. 



Shell larjje, thick, equivalve, subcircular in outline, convex; surface sculptured by many 



obsolete, concentric lamelke, and fine, incremental lines; lunule deeply impressed, small, fmcly 



scul|)tureil; beaks small, not elevated; hinge very wide and heavy, with three heavy, cardinal teeth, 



the posterior one in the riq^ht valve being bifid; ligament long, narrow, sunken. 



Dimensions. — Long. 119 mm.; alt. 105 mm.; diam. 55 mm.; lunule 15 mm. 



Coimuou in the upper San Pedro series (Pleistocene) of Twenty-sixth Street, 

 San Diego. 



Livhuj — West Mexican coast to Panama (Carpenter). 



Pleistocene. — San Diego (Hemphill; Arnold). 



Pliocene. — Kirker's Pass, Contra Costa County; San Fernando (Cooper): 

 Stanford University, Santa Clara County (Arnold). 



Genus Venus Linne. 



Shell thick, ovale, smooth, sulcated, or cancellated; margins minutely crenulated; cardinal 

 teeth three in each valve; pallial sinus small, angular; ligament prominent; lunule distinct. 



Venus verrucosa Liniu' is a characteristic species. 



[S. B.] Venus perlaminosa Conrad. 



Mercenaria perlaniinosa Con., Proc. Phil. Acad. Sci., 1855, p. 267. Gabii, Pal. Cal.. Vol. II, 

 pp. 22, 55, 94; PI. V, fig. 38; PI. XV, fig. 14; 1869. Cooper, 7th Ann. Rept. Cal. St. 

 Min., 1888, p. 250. 



Venus keimerleyi Rve., Icon. Conch. ( Venus), PI. XII, fig. 41 (_/ide Gabb). 



"Shell large, thick, rounded, subquadrate, very inequilateral; beaks anterior; anterior end 

 excavated under the beaks, rounded below; base broadly rounded; posterior end convexly truncated; 

 cardinal margin slightly convex. Surface closely marked by numerous prominent, recurved, 

 lamelliform concentric ribs. Lunule marked by an impressed line. Hinge robust. Pallial line 

 strong, sinus small, oblique, acute at base; muscular scars nearly equal in size; margin minutely 

 crenulated; the purple color between the pallial line and the base is very persistent. "^ — [Gahb.] 



Found in the Pliocene at Packard's Hill, iuul in the Pleistocene at the bath- 

 house, Santa Barbara. 



